Light-absorbing dielectric compositions

Abstract

A composition for making fired dielectric layers which is especially suitable for laser scribing consisting essentially of finely divided particles of dielectric glass, inorganic filler having a refractive index higher than the glass and cobalt oxide, all being dispersed in organic medium. The composition can be in the form of either thick film paste or green tape.

We claim: 
     
       1. A composition for making fired layers which are especially suitable for laser scribing consisting essentially of finely divided particles of: (a) 68.0-94.99% wt. dielectric glass;   (b) 5-30% wt. inorganic filler having a particle size between 0.3-3 microns and a refractive index at least 0.07 higher than the refractive index of the dielectric glass; and   (c) 0.01-2.0% wt. cobalt oxide having a particle size less than 5 microns and is selected from CoO, Co 3  O 4  and mixtures thereof, all of (a), (b), and (c) being dispersed in;   (d) an organic medium.   
     
     
       2. The composition of claim 1 in the form of a thick film paste in which the organic medium is a liquid solution of polymer in nonvolatile solvent. 
     
     
       3. The composition of claim 1 in the form of a green tape in which the organic medium is a solid matrix of solvent-free organic polymer. 
     
     
       4. The composition of claim 1 in which the filler is selected from Al 2  O 3 , ZrO 2  and mixtures thereof. 
     
     
       5. The composition of claim 1 in which the glass has a refractive index between 1.4 and 1.7. 
     
     
       6. The composition of claim 2 in which the organic medium is comprised of ethyl cellulose dissolved in beta terpineol. 
     
     
       7. The composition of claim 2 in which the organic medium is composed of an acrylate or methacrylate polymer dissolved in Carbitol™ acetate (diethylene glycol mono ethyl ether acetate). 
     
     
       8. The composition of claim 1 in which the glass is an amorphous partially crystallizing glass. 
     
     
       9. The composition of claim 1 in which the glass is an amorphous non-crystallizing glass. 
     
     
       10. The composition of claim 1 in which the glass is an amophorous totally crystallizing glass.